Henri schaede



H. SCHAEDE HYDRAULIC BRAKE Aug. 28, 1928.

Fiied July 28. 1926 Patented Aug. 28, 1928.

UNITED STATES 1,682,308 PATENT OFFICE.

HENRI SOHAEDE, OF LIEGE, BELGIUM.

HYDRAULIC BRAKE.

Application filed July 28, 1926, Serial No. 125,581, and in Belgium August 4, 1925.

My invention relates to and is an improvement in hydraulic brake apparatus of the character in which the brake operation is separated intottwo phases and by means of a pump receiving its action from the wheels of the car.

The object of my invention is to provide a brake apparatus of-the above general character, in which the pump during the normal running of the car, maintains continuously a closed circulation in an invariable direction whilst during the braking action the liquid pressure is sent first on a pistonassociated with a second larger piston, which is connected'to the brake-shoes and thus sucks liquid from a reservoir at constant volume or from a compensating reservoir in order to apply the brake-shoes. In the second phase of the operation, the pressure from the pump is exerted on the larger piston so as to realize the full application of the shoes on the wheels of the car.

A further object of my invention-is to provide a device of the last mentioned character in which the-brake action may be made variable and is automatically effected in case of breaking the electric circuit utilized to control the brakes of the several cars of a train.

Other objects will be in part obvious from the annexed drawing and in part lndicated in connection therewith by the following analysis of the invention. 1 In the accompanying drawing, is illustrated a diagrammatical View of the general arrangement of parts in normal position.

The rotation of the wheels of the car causes the running of a little rotary gear pump sucking through an admission pipe 2 the brake liquid, oil or the like, contained in a reservoir at constant volume 3 to send it through an exhaust pipe 4. to a brake-valve 5, which during the normal running of the car is normally moved from its seat allowing the liquid to return to the reservoir 3 through the pipe 6 connected to the admission pipe 2.

The pump 1 is-constructed in such a manner that, whatever may be the direction of running of the car, the liquid is always admitted by the pipe 2 and is always expelled through the exhaust pipe 43 In the-forward movement, the liquid passes from the admis* sion pipe 2 in a channel 12 of the pump through an'automatic admission valve 9, and thence in the exhaust pipe 4 through the exhaust valve 14. In the reverse movement, the liquid passes from the admission pipe 2 in a channel 10 of the pump through an autois prolonged by a supply and release pipe 17 leading to a c linder 19, in which moves a piston 24 associated with a piston 25 of larger diameter, pressed by a release spring23 andconnected to the brake rigging 33. The pressure exerted on the valve 16 by a sprin 22 belng more than the pressure of there ease spring 23, the valve 16 is normallyheld to its seat, the liquid being thereby obliged to go to the reservoir 3. Both valves 5 and 16 are connected by a s ring 27 holding them nor- -mally seated, whi e an electro-magnet 26 acts to raise them, when the electric circuit is closed. The lift of the valve 5 is made easier by means of a spring 57 The pipe 18 leads from the valve 16 to a valve-casing in which is provideda valve 38 controlling the communlcatlon between the reservoir 3 and a compensating reservoir 21, provided with a sleeve 52 and closedby a filling plug 51. From the bottom of the reservoir 3-, 1n which moves a plunger 32 pressed by a spring 39 and adustable by means of a set-screw, leads a pipe 29 to the large brake-cylinder 20. In said pipe 29 is interposed a casing containing two valves, one of which 30 regulates the com munication between two sections of the pipe 29, while the other 45 regulates the communication between the brake-cylinder 20 and a branch ipe 66, leading to the pipe 17, a little under e point where the latter is prolon ed by a pipe 36 communicating wit the cy inder 20 by means of a by-pass pipe 37.

Having thus described the essential elements of the brake apparatus, the operation of the latter is substantially as follows. When-it is desired to make an application of the brakes, the tension residin in the circuit 46 of the electro-magnet 26 IS reduced by means of a servo-controller connected to a battery 42. The spring 27 exerts therebyb means of the driving lever 28 a ressure equal: by way of example, to P .poun s on the valve 16 and to 2P pounds on the valve 5." The liquid exhausted under pressure by the pump I The larger piston 25 is simultaneously moved with the piston 24, sucking thus from the reservoir 3 through the pipe 29 and the valve 30 the full volume of the cylinder 20. Theoretically, the volume of the reservoir 3 corresponds to the releasing quantity of the brake-c linders 19 and 20, which quantity is adjustably by means of the set-screw 31,1im-

iting the stroke of the plunger 32. The releasing quantity of liquid comprises thus: the liquid sent back by the flection of the riggings 33 and the liquid sent back bythe pistons 24 and 25 pressed by the release spring 23 owing to the clearance between the shoes and the wheels.

Thefirst phase of the brake operation is thus ended. During this preliminary phase,

" the volumeof the reservoir 3 has been drawn:

1 by the pum 1 to send it tothe cylinder I 19; 2 by the piston 25 to fill the cylinder 20.

pressure generated in t At the end of this phase, the plunger 32, the position of which has been adjusted for'each car to a determined play of X mm., to the shoes, thus comes to the end of its stroke with, its nose 34 restinlgl on a stop 35. The e pipes 4, 17 and 36 y the continuous action of the pump 1 is then transmitted into the brake-cylinder 20 through the by-pass 37, so that by the in-- creased" ressure the larger piston 25 is forced forwar and applies the brakes, thus realizing the second phase, that is to saythe effective braking. During this operation the reservoir 3 having been totally emptied, theliquid circulation is established as follows: from the compensating reservoir 21 to the pump 1 throug the valve 38 and the cylinder 3, from the pump 1 to reservoir 21 t rough the valve 16 and pipe 18 and so on. The piston 32 acts on the valve 38 to hold it "loaded so that the pump draws preferably out of the reservoir 3; the suction of the-pump thus being lightly in load, the volume efliciencyiis a maximum.

By varying the intensity'of the current in the electromagnet26, the braking force may be moderated, the spring 27 exertin on the valve 16 a force proportioned to this variation, so that the corresponding pressure realized in the brake-cylinders regulates the force of the braking action. For this purpose, a suitable resistance 41, connected with coil 26, is switched on the battery 42 by means of the servo-controller 40, or the current of anelectric line 43 comprising a resistance 44 .is utilized, so as to reduce the current in order to prevent any danger inmanipulating the plugs 48 connecting the coupled cars together.

During braking action the wear of the shoes is continuously compensated by the pressure exerted by means of the liquid sent by the pump 1 to the cylinders 19 and 20. When the clearance between the shoes and the wheels is increased before the braking action, the volume of the reservoir 3 being insuflicient in operation, the pump 1 draws the liquid from the compensating reservoir 21 through the valve 38 pressed by the spring 39 of the plunger 32 so as to send the necessary supplement of liquid into the brake-cylinders, which supplement remains in said @0 cylinders, as the brakes are released, thus restoring the normal determinedclearance. On the contrary, when the clearance is reduced between the shoes and the wheels before the braking action, the volume of the reservoir 3 being too large in operation, is drawn out b the pump, but the excess of liquidinstea of going tothe brake-cylinders, passes through the valve 16 to the compensating reservoir 21, thus the reservoir being totally empty as the brakes arereleased, the clearance becomes again normal.

The immediate and complete releasing of the brakes is obtained by giving the maximum current to the electro-magnet 26, thus an: nulling the action of the s ring 27 on the valve 6, which is unseated w ile the valve 16 is subjected always by the spring 22 to a pressure a little superior to that of the spring 23 of the riggings. The emptying of the cylinders 19 and 20' is made immediately, the liquid returning in the reservoir 3 through the pipes 29, 17, 6, 2 and the valves 45 and 5. For the purpose of moderating the releasing of the brakes during the running of the car, the tension of the circuit 46 and thereby the forceapplied on the valve 16 through the spring is regulated at will.

In order to give the full play to the rigging and to provide for new brake-shoes, it is sufficient to remove the valve spring 22 so that the liquid escaping totally into the reservoir 21 the releasing is made total. The brake apparatus is operated, as it has been said, by means of the servo-controller 40, which is located in the motor cars, when said apparatus is appliedto a trainand the several cars are connected by means of low voltage unipolar plugs 48. Each car in turn comprises a handle driving lever 50 connected by means of a chain 49, or any other suitable device to the valve lever 28 so that the brake apparatus of each car may be independent one from another and a detached car may be thus worked without the help of the motor car carrying the electric driving device. When the coupling sections are disconnected, the electric circuit 46 is broken, the spring 27 holds the valves 5 and 16 to their seats thus producing an automatic and complete braking. A switch 47 short circuiting the electroswith the body serves as an alarm signal thus efiecting the maximum braking-of the train.

The security assured by the above described brake apparatus may be increased by the possibility of suppressing any slipping of the wheels. The pipe 29 is connected to the branch pipe 66 though a by-pass 65 obturable by means of a check valve 61 subjected to the opposing actions of a spring 62 and of an electromagnet 59 connected to an electric circuit 63, and to a switch 64. When the wheels are slipping, the pump 1 exhausting no more, the piston 24 is locked too strong and causes the liquid to escape a little through the bypass 65, so that the wheels are automatically delivered and begin again to rotate.

The complete stop of the car or of the train, according to the application, is obtained by breaking the circuit 63, by means of the switch 64, thus the tension in the electromagnet 59 being null, the spring 62 holds the valve to its seat and the by-pass '65 being closed a maximum braking is obtained.

. Practically the driving of the controller 40 may be combined with the switch 64 in order to have only one driving lever to be actuated by the motorman.

I claim asmy invention and desire to secure by Letters Patent- 1. In a brake apparatus, the combination substantially as set forth of a pump to be operated continuously from a car-axle and to deliver liquid always in the same direction whatever may be the direction of rotation of the car, an exhaust pipe connecting said pump to a casing provided with a cont-rolling valve, a supply and release pipe leading from said valve casing to two brake cylinders, pistons of different size fitted in said cylinders and associated together, a retracting spring bearing on said larger piston, connected'to the rigging of the car, a reservoir at constant volume and a compensating reservoir supplying the brake liquid, a valve controlling the communication between said reservoirs, controlled means for connecting said brake cylinders and said pump to said reservoirs, means for driving electrically the controlling valve.

2. In a brake apparatus, the combination substantially as set forth of a pump adapted to be operated continuously from a car-axle, an exhaust pipe connecting said pump to a casing provided with a controlling valve, a brake lever connecting said valve to a regulating valve controlling the return of the liquid from the cylinders to the compensating reservoir, a sprlng acting on said brake lever to hold the controlling valve to its seat and thus determine the application of the brakeshoes, an electromagnet-controlled'by means of a servo-controller located in the motor car, to act on the brake lever in direction opposite to that of said spring and to cause a continuous circulation of liquid during the normal running of'the car, a handle lever connected to said brake lever in each car to replace the electro-magnet when the coupling connec tions of a train are disconnected.

3. In a brake apparatus, the combination substantially as set forth of a gear pump adapted to be operated continuously from a car-axle and provided with a pair of admission valves and a pair of exhaust valves connected together respectively in the casing of said pump through suitable channels in order to deliver liquid always in the-same direction whatever ma be the direction of rotation of the car, an ex iaust pipe connectin said pump to the supply and release pipe and thereby to the brake cylinders, pistons of diflerent size fitted in said cylinders and associated to- Y gether so that when the smaller piston re ceives the pressure of liquid the larger piston draws from the reservolr at constant volume or from the compensating reservoir.

4.,In abrake apparatus, the combination substantiall as set forth of a gear, pump adapted to e o erated continuously from a car-axle, an ex aust pipe connecting said,

pump to the supply and release pipe and thereby to the brake cylinders, pistons of different size fitted in said cylinders and associated together, a retracting spring bearing on said larger piston connected to the rigging of the car, a pipe connecting the larger cylinder to a reservoir at constant volume, a valve casing joining the two portions of said pipe, and provided with valves for regulating the admission and exhaust to and from the large cylinder; a pipe connecting said pipe to the supply and release pipe and controlled by a check valveto permit the escape of an excess of liquid from the large cylinder when the wheels are slipping, a spring pressing said valve to obturate the pipe, an elect-ro-magnet acting on said valve to open the pipe, a switch combined with the servo-controller driving the brake applying mechanism and located within the reach of the motorman.

In testimony whereof I aflix my signature. HENRI SCI-IAEDE. 

